Question


Answer

a^2+b^2+c^2-ab-bc-ac

=\dfrac{1}{2} (2a^2+2b^2+c^2-2ab-2bc-2ac)

=\dfrac{1}{2} [(a-b)^2+(b-c)^2+(a-c)^2]

≥0

Steven Zheng posted 2 months ago

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